Diesel Generator (DG) Flashcards
What is the continuous rated KW output for Diesel generator ?
5500kw
What is the intermittent output ?
6050KW (2hr in a 24hr period)
What is the continuous rated HP output ?
7670HP
What does the DG system respond automatically to ? What does diesel generator automatically start on ?
ESFAS signal:
-Safety Injection Actuation Signal(SIAS)
-Auxiliary Feed water Actuation Signal(AFAS)
-Loss Of Power(LOP)
-Containment spray actuation signal(CSAS)
What’re the 3 modes on the selector switch ?
OFF/LOCAL/REMOTE
What is the OFF position used for ?
-Used during maintenance to inhibit automatic,local,and remote starts.
-send alarm to Local control room and Main control room
What is the Local position used for ?
-Able to manual start diesel generator
-Diesel generator will be able to start on an emergency signal
-NO remote start
What is remote start used for on selector switch?
-Can be started from Main Control room or from emergency signal
-Local manual start control panel disabled
What’re the Manual Start & Stop push buttons?
-Manual start will start DG in test mode
-Manual Stop will stop DG only if in test mode
What do the Emergency start push buttons do ?
Will start DG in emergency mode:
-Simulated LOP
-Simulated ESF actuation
What’re the Emergency Stop and Reset push buttons for ?
-Emerg. Stop button will open DG output breaker and stop it without 5 minute cooldown (Will Alarm)
-Reset button clears the stop signal to allow DG to be restarted
What’re the First Out and System reset buttons used for ?
-Reset all cleared alarms on the local DG control panel
-Verify with control room no active signals are active that’ll auto start Emerg. Mode when pressed
-First Out system provides indication, by different alarm flash sequence, of first trip signal that caused DG trip
What is the Emergency Mode interlock defeat switch for ?
Key locked control mode selector:
-OFF position allows DG to start and run in Emerg. Mode. This is normal position
-ON position returns DG to test mode from Emerg run conditions
How will the DG start on a LOP signal ?
The affected Train DG will automatically start & output breaker will auto close if conditions are met
What conditions will a LOP of power be initiated on PB bus ?
Degraded voltage- 90%(30seconds)
Under voltage- 75%(instantly)
How will the DG start on a SIAS signal ?
-Both DGS will start in Emerg. Mode in a no load standby position.
-DG output breakers stay open and must be manually closed
How will the DG start up on a Auxiliary Feed Water Actuation (AFAS)signal ?
-Both DG start up in Emerg. Mode no load, standby position
- Output breaker stay open, until manually closed
How will DG startup on a Containment Spray Actuation Signal (CSAS)?
-Both DG start in Test Mode in no load ,standby position
-Output breakers remain open and must be manually closed
How’re SIAS & CSAS signals generated ?
Generated from Containment pressure rising:
SIAS-3 psig
CSAS-8 psig
How will the DG operate while in Emergency mode ?
-Will operate in isochronous mode with frequency at 60HZ
-Emerg. Mode light will be lit on local control panel
How will DG operate if started in Test Mode?
-Will operate in droop mode,speed and voltage will be in predetermined position of DG speed and voltage adjustment potentiometer setting
How do you check what Run Mode the DG is in ?
By looking at local control panel and seeing the Emerg. Mode Light
What conditions need to be met for ESFAS load sequencer, to auto close output breaker ?
-DG at rated speed:600rpm
-DG at rated voltage: 4.16kv
-No faults on PB buses Normal or Alt. Breaker (86 lockout)
-Both Norm. & Alt. breakers for respective Train Class bus are open
-LOP signal
What’re necessary conditions for the DG output breaker to be closed locally ?
DG output breaker should only be closed on a dead bus when DG output breaker is being closed locally
What is the DG Starting Air Subsystem for ?
-Provides storage and control of compressed air to start the Diesel Generator
How does air start the Diesel Generator?
Provides pressurized air to the top of the pistons, which turns the crankshaft
What Non-Safety/Safety related components does the Starting Air System have ?
Non-Safety:
-Two redundant air compressors
-Two redundant coalescing filters and air dryers
Safety related: (PER TRAIN)
-Two air receivers
-Two engine starting air control valves
-Two air distributors
-Twenty starting air valves(on cylinder head)
Where do the compressors draw air from and how is moisture removed from compressed air before being stored?
-Draws from ambient air through Intake Air Filters
-Air dryers remove moisture before going into Air Receivers
What is the Air receiver constantly aligned with ?
The Starting Air Control Valves
Where does the small air line that is tapped off just before the Starting Air Control Valves send air to ?
-Control air filters
-Mechanical turning gear interlock control valves
-Starting air solenoid valves
-Shuttle valve that opens starting air control valves
What is the second flow path of the small air line coming just before Starting Air Control Valves ?
-Through shuttle valve
-Control Air Filter
-Control Air Network
What is the air regulated for Control Air Network ?
-80psig for Emerg. Run trips and control cylinder
-37psig for operation of Test Run Trip Header and temperature control for intercooler heater core
When will the Air Solenoid Valves open and provide air through the shuttle valve to the starting air control valve ?
On a automatic start / manual start of diesel generator
What happens when the engine reaches 280RPM ?
The Starting Solenoid Valves will de-energize and will depressurize, and diesel engine will take over
What is the air pressure that starts the Diesel Generator at ?
250psig
What powers the air compressor motors ? What is the relief valve discharge pressure set point?
-NH system powers 15HP motor
-265psig will open relief valve protecting the system
When will the air compressor START/STOP? What kind of switch does the air compressor have ?
- Will receive a start signal when Air Receiver reaches 240 psig
-Will stop when Air Receiver reaches 250 psig again
-Compressor has Auto/Stop and Start, which is normally in Auto/Stop
What is used to keep the oil warm and moisture free inside the air compressor?
-There is an immersion heater with a Temp. Switch
-If oil temp. to low it’ll kick on heater
How are you supposed to check oil level on air compressor ?
-Glass gauge isolation valve must be open to check oil level
-Must also be closed when in operation
What’re Intercooler & Aftercoolers for ?
Intercooler cools the air between 1st & 2nd stages, and between 2nd & 3rd stages of the compressor
Aftercooler cools the air discharging from 3rd stage going to the air dryers
How does the compressor provide cooling to the intercoolers and after coolers ?
It uses the belt-wheel fan ON the compressor to blow air across intercooler fins
What is done to prevent condensate build up in compressor ?
Condensate is drained from 2nd stage intercooler & aftercooler
What’re the air dryers comprised of ?
Precoolers/preheaters,separators, and typical chiller package
How does air dryer chiller package work ?
Uses refrigerant to lower temp and dew point of compressed air, which separates moisture from the compressed air.
Where do the Air dryers receive their power from ?
NH system
How many Diesel Starts from a full 250psig charged Air Receiver?
You can get 5 Diesel starts from a full Air Receiver
Where can Air receiver pressure be monitored at ?
Locally on the Air receiver & on the DG control panel
When will an Air Receiver common alarm come in on the local DG control panel ?
-If the isolation valve on outlet of receiver is closed
-If Air Receiver pressure falls below 185psig and isn’t restored above 185 psig after 3 minutes
What’re the two outlet flow paths for the Starting Air Control Valves ?
-Outlet from main valve goes to Starting Air Header (Normally closed unless engine start signal is received)
-small secondary outlet provides control air
Why must Air Receiver always be applying compressed air to the Starting Air Control Valves ?
-To supply engine Control Air system
-To have the ability to automatically start
Why is there two solenoid valves ? When will will these solenoid valves open ?
-There is two just in case one fails, it won’t affect an emergency startup
-Solenoids will open on a engine start signal , which will open the Starting Air Control Valve
Why’re the Starting Air Headers cross connected?
Just in case one Starting Control Valve fails, both starting air header will still be able to receiver 250psig from the working control valve
What opens the Starting Air Valve(Cylinder Head) ?
The Starting Air Distributer pushes air(250#) down on piston, which eventually overcomes spring force and opens the Starting Air Valve, letting Starting Header Air pass into the cylinder. Which turns the crankshaft to start engine
Where is the Starting Air distributer located on the engine ?
Located at toward end of the engine, which is driven by camshaft through a splined shaft
What is the Air Distributer used for ?
It times which Starting Air Valves open and close in the correct sequences during an engine start
What prevents condensation in the Starting Air Header & any combustible leak by from cylinders?
Small amount of air is pulled off discharge of compressor and send it through Starting Air Header and is vented through Starting Air Control Valve
What pressure is sent to the turn gear assembly? What happens if a start signal is initiated while turning gear is engaged ?
-A pressure regulator reduces 250psig to 100psig, which is sent to turning gear
-There is an interlock that won’t let Starting Air Control Valves to be opened
What is the Tech Spec that is associated with Starting Air subsystem?
-Need one Air Receiver capable of delivering 230psig (allows 5 startups)
-Ensure DG is able to start in time
What do the Air Intake and Exhaust subsystem do for diesel engine ?
-Intake provides clean cool air at a high pressure for efficient combustion
-Exhaust discharges exhaust gases to atmosphere
-Has intake silencers
What is the intake flow path?
Goes through Air filter, Air intake silencer, Overspeed Butterfly Valve,& Suction of Turbocharger compressor
What is the exhaust flow path ?
-Exhaust gases leave combustion chamber and goes to exhaust manifold
-Flows hot air into the Turbocharger Turbine causing it to spin
- discharged of turbine flows exhaust to exhaust silencer and discharges to atmosphere
How do the Air intake filter work ?
Uses an oil bath to remove dust and particles from air
How does the Intake Silencer work ?
Uses baffles to reduce noise going to turbocharger
When does the Turbocharger Butterfly Valve trip ?
It trips on 660 RPM, which will shut off air supply to combustion chambers and stops the engine
How do you reset a tripped Turbocharger Butter fly Valve?
Manually reset by resetting overspeed governor and pulling butterfly handle until latches
-This is the only direct mechanical trip that’ll trip the DG on overspeed
What is the TurboCharger lubricated from? What cools the Turbocharger ?
-It’s lubricated by Engines Lube Oil system
-Cooled by Engine Jacket Water system
What is the intercooler heater used for ? Where does the intercooler get its heat from ?
It keeps the intake manifold warm so diesel can start up in 10 seconds. It keeps it warm by sending warm jacket water through intercooler
What is the large intercooler cooler on the intake flow path used for ? Where does it get its cooling water from ?
-It’s used to cool the air that was compressed by the turbocharger
-Receives its cooling from spray ponds
Where are all major components of the Fuel supply located ?
Located:
-On the engine
-Auxiliary Skid
-136ft of Diesel Building
-South of control building in vault underground
What’re the major components of Fuel Oil Storage subsystem ?
-Fuel Oil Storage Tanks
-Fuel Oil Transfer Pump
-Fuel Oil Supply Headers Strainers
-Fuel Oil Day Tanks
What’re the major components of Fuel Oil Supply subsystem? (Delivers fuel from Fuel Oil Day Tanks to high pressure fuel subsystem )
-Duplex Fuel Strainer
-Engine-Driven Booster Pump
-Duplex Fuel Filter
-Engine Head Tank
-Fuel Injection System
-Fuel Drains
What is the High Pressure Fuel subsystem for? What’re major components of the system ?
-The system provides fuel to cylinder according to main governor demand.
Components:
-Injection pump
-Fuel Injector
What is the flow path for the Diesel Fuel Oil and Transfer subsystem?
1.)Fuel Oil Transfer Pumps transfer fuel from storage tanks
2.)Through 1of2 Fuel Oil Supply header Strainers
3.)To associated train Fuel Oil Day Tank
When does Fuel Oil Transfer pump Start & Stop ?
Starts at 731 gallons and stops when it reaches full capacity in the Fuel Oil Day Tank
What’re the Cross connect lines for on the Fuel Oil Transfer system ?
So that either Transfer pump can discharge to Fuel Oil Day tank supply redundant DG.
What’re the modes that can’t have cross connections in fuel supply system ?
Normal operations:
1,2,3,4
It would violate independence and redundancy